On Oct 5, 2005, at 9:44 AM, Tim Ellison wrote:
Geir Magnusson Jr. wrote:
I'm working with Dan's bootVM to get to run on Windows, and have been
thinking about the use of -fpack-struct vs #pragm pack() vs just not
packing and writing code that is a little slower, and a little more
I'd dispute that packing always produces faster code, but...
I wasn't suggesting the packing itself made things faster, but if a
1000 field structure :b maps directly onto a buffer, memcpy() is your
friend...
verbose, but seemingly more robust and maintainable due to less
information about context needed to avoid surprises.
I've reconfirmed that packing structs is deadly when you want to call
into standard libs
struct stat foo;
stat("foo.txt", &foo);
does some bizarre things :)
So how do people deal with this these days? I know fashions change,
and I haven't done C in anger for > 6 years... (I still have the
shakes when looking at it - I'm past the screaming stage...)
Just use the compiler's default (ANSI) layout behavior, and then
explicitly pack a struct using pragmas only where required -- usually
for layout compatibility with an external binary.
As you illustrate above, packing somebody else's struct definition can
bring you into conflict with their binary's view of the world.
Yep - that's what I've done w/ bootJVM, and it works just fine so far..
geir
--
Geir Magnusson Jr +1-203-665-6437
[EMAIL PROTECTED]
